The specific aims of this research are i) to purify the intracellular and secreted forms of human chorionic gonadotropin (hCG) subunits produced by malignant trophoblastic cells and normal placents, ii) to characterize biochemically the intracellular and secreted forms of HCG subunits produced by these tissues and, iii) to determine the ratelimiting steps involved in the processing and secretion of HCG subunits by these tissues. Methods will include pulse-chase labeling of cultured trophoblastic cell lines and organ cultures of normal placenta with radioactive amino acids and carbonhydrates, determination of carbohydrate structure and amino acid composition and sequence of the glycoprotein subunits of hCG produced by these tissues, and use of immunocytochemical techniques for intracellular localization of hCG subunits. The long term objectives are i) to learn what controls the secretion of hCG from normal and malignant trophoblastic cells, ii) to determine what differences, if any, exist between the glycoprotein hormone subunits produced by normal and malignant cells, and iii) to determine of the secretion of hCG subunits by trophoblastic cells can be pharmacologically manipulated. The results of these studies will have potential significance for the use of hCG subunits as tumor markers and in fertility control.